Harmonically modulated luminescence: Bridging gaps in carrier lifetime metrology across the PV processing chain

Carrier lifetime measurements via harmonically modulated luminescence have considerably evolved recently, giving rise to numerous relevant advances and applications in materials science. An essential asset of this technique lies in its unified applicability across the photovoltaic processing chain-from ingots to solar cells. This paper shows how present gaps in carrier lifetime metrology are overcome via harmonically modulated luminescence by focusing on the complete theoretical understanding of harmonically modulated lifetime, on its unmatched bulk lifetime contrast for silicon ingots, and on the capability to monitor the metalization process. Practical considerations for a straightforward (and spatially resolved) ingot bulk lifetime extraction via harmonically modulated luminescence are detailed and validated. Example lifetime investigations demonstrate this technique's capability of bridging the addressed conceptual and instrumental gaps.